Current state of the art trace detection for explosives, chemical threat agents, and other threat agent signatures have remained long-standing goals of modern instrument platforms. However, analytical techniques for direct vapor detection of threat agents remain limited because significant improvements in sensitivity must yet be attained if automated technologies are to be of practical use. For example, equilibrium vapor pressures (saturated) of RDX explosive at 25° C. provide a concentration of ˜6 parts-per-trillion (ppt) or 6 in 1012. Because real-world analyses must achieve detection below saturation levels, sensitivity must be substantially better than this 6 ppt threshold. To complicate matters, improvements in sensitivity without improvements in selectivity are counterproductive, as increasing sensitivity effectively raises the chemical noise, which offsets improvements to upstream components. Thus detection of threat agent vapors requires significant increases in sensitivity along with subsequent increases in selectivity. While some sensitivity and selectivity improvements have been achieved with mass spectrometry (MS)-based analytical approaches including, e.g., Selected Ion Flow Tube (SIFT) Mass Spectrometry (MS) or (SIFT-MS); Proton Transfer Reaction Mass Spectrometry (PTR-MS); and Atmospheric Pressure Chemical Ionization Mass Spectrometry (APCI-MS), none of these approaches provides selective determination of vapors from explosives and other threat agents. Nor do these approaches achieve sensitive and selective trace level detection of threat agents in real-time.
Accordingly new systems and processes are needed that enable real-time trace level detection of explosives and other threat agents at a parts-per-trillion level or better. The present invention addresses these needs.